522301 ModularHose 3" Mounting Disc for 3/4" ID System, pack of 1.Flat surface allows for easy attaching of items such as head switches, small devices, and more. Attach using optional Velcro, Dual Lock, or similar. The design also allows for the disc to attach to something (using it as a base) such as a desk or table. (Replaces 520001 & 90610)